1. Field of the Invention
The present invention concerns a method for production of trinitro compounds. Specifically, the present invention relates to a method for the production of trinitromethane (nitroform) by the reaction of nitric acid with isopropyl alcohol.
2. Description of the Prior Art
It was known heretofore (Orton and McKie, JCS, 1920) that nitroform could be produced by introducing acetylene gas into concentrated nitric acid under catalysis with mercury salts. In this manner a solution is obtained which contains approximately 70-90% nitric acid, 5-11% nitroform, the remaining solution comprising water, small amounts of oxalic acid, etc.
Nitroform (trinitromethane) is a very valuable compound for use in the preparation of explosive and propellant ingredients, due to its high oxygen content and labile hydrogen atom, which facilitates the preparation of trinitromethyl and fluorodinitromethyl derivatives. Of particular interest, is the use of nitroform for the preparation of bis(fluorodinitroethyl) formal (FEFO) and 1,3-bis(fluorodinitroethoxyl)-2,2-bis(difluoroamino) propane (SYEP). Both FEFO and SYEP are energetic plasticizers that are being utilized in advanced solid propellants. Consequently, low-cost processes for their production are required. This, of course, necessitates starting their production with low-cost nitroform.
An industrial scale facility for the production of trinitromethane based on the reaction between acetylene and nitric acid was reported by A. Wetterholm, Tetrahedron, 1963, Vol. 19, pp. 155-163. The industrial plant which utilized a mercury catalyst comprised three basic elements, namely, a nitrator for the oxidation nitration reaction, a distillation system consisting of one or more fractionating towers and an evaporator, and equipment for concentrating the dilute nitric acid, which was formed during the reaction. A maximum yield of approximately 75% was obtained. A disadvantage of this process is the requirement for the mercury catalyst. Specifically, for the process to be economical, the nitric acid must be recovered for reuse in the process, and the separation of the nitric acid from the mercury catalyst is difficult. In addition, the use of a mercury catalyst substantially adds to the cost of the process. Obviously, therefore, it would be desirable to have a process for the production of trinitromethane which did not involve the use of an expensive catalyst, and which would be safe and economical.